A global strategy to prepare a versatile and robust reactive platform for immobilizing molecules on carbon substrates with controlled morphology and high selectivity is presented. The procedure is based on the electroreduction of a selected triisopropylsilyl (TIPS)-protected ethynyl aryldiazonium salt. It avoids the formation of multilayers and efficiently protects the functional group during the electrografting step. After TIPS deprotection, a dense reactive ethynyl aryl monolayer is obtained which presents a very low barrier to charge transfer between molecules in solution and the surface. As a test functionalization, azidomethylferrocene was coupled by "click" chemistry with the modified surface. Analysis of the redox activity highlights a surface concentration close to the maximum possible attachment considering the steric hindrance of a ferrocenyl group.

International audienceThe electrogeneration of aryl radicals from protected diazonium salts combined with protection-deprotection steps was evaluated to design functional monolayers on carbon substrates with a well-controlled organization at the nanometric scale. The structure of the obtained monolayer is adjusted by varying the size of the protecting group that is introduced on the precursors (trimethylsilyl, triethylsilyl, and tri(isopropyl)silyl were tested in the present study). After deprotection, a robust ethynylaryl monolayer is obtained whatever the substituent that serves as a platform to attach other functional groups by a specific "click chemistry" coupling step. Electrochemical and structural analyses show that the organization of the attached monolayer is totally governed by the size of the protecting group that leaves a footprint after removal but maintains a total availability of the immobilized functional groups. Properties of the monolayer (charge transfer, permeation of molecules through the layer, density of functional groups) were examined in combination with the performances for postfunctionalization taken with an alkyl-ferrocene derivative as an example of the immobilized species